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In this paper, the model of BGA solder joints were established by the finite element method (FEM). It would reflect the variations of creep stain in solder joints more truly by the cyclic temperature loading. The results are as follows: when the BGA solder joints subjected to cyclic thermal loading, the equivalent creep strain move to the center of solder joints gradually with the increase of the...
In this paper, we present an unstable phenomenon in cascaded systems that the source converter might become unstable after connected with the load converter though it can work stably individually. However, by staggering the switches' turn-on time between the source converter and load converter, it can become stable. Analysis in this paper shows that the essential reason for this phenomenon is that...
This paper presents the magnetic field modeling-based energy efficient routing for WSN which models the routing problem as a current-carrying solenoid and a free to turn magnet put into a uniform magnetic field respectively. The optimal routing is then performed through the path with the maximum generated magnetic field intensity for the solenoid technique and with minimum torque for the magnetic...
In multi-timestep Optimal Power Flow (OPF) formulations, constraints that are time-dependent such as generator ramp limits and specifically energy storage constraints may cause the Jacobian matrix to become singular as the problem iterates towards the optimal solution. The particular case of this singularity happens when the gradients of the binding intertemporal constraints are linearly dependent...
Aiming at the main steam temperature control problem of ultra-supercritical units under variable loads conditions, a predictive PID control algorithm with layered structure is proposed. The cascade PID control is applied in the lower circuit which can realize the application in DCS system through configuration language programming. The generalized predictive optimization is applied in the upper circuit...
Electric vehicles attract around the world for its energy conservation and environmental protection, which is a major development direction of the promotion of the use of new energy. With the development of electric vehicles, it possible that large-scale electric vehicles connect to the grid, which will bring new challenges to the security and stability to the grid. Reasonable management and control...
This paper presents a parameter identification method with nonlinear ordinary differential equation (ODE) model for electro-hydraulic servo systems (EHSS) based on Matlab toolbox, in which the values of known parameters are fixed and the values of unknown parameters are identified. In order to avoid the problem of over-parameterization, this paper divides the identification into two parts, i.e. no-load...
This paper introduces the structure of gigahertz TEM cell (GTEM cell). And the Finite-Difference Time-Domain (FDTD) method is used to model electromagnetic field of effective work space of GTEM cell accurately. The effect of meauring system put at the effective work space is also analyzed. This work will offer theory direction of electromagnetic field distribution of effective work space of GTEM cell.
In this paper, we assume that the bounded-wave simulator is placed on the ground in the experiment. And the finite-difference time-domain (FDTD) method is used to model electromagnetic field at working region. From the numerical result, we can see that the ground has great effect on the electromagnetic wave.
To address the problem of approximation and prediction of complex time-varying system, this paper proposes a parallel process neural networks predication method based on general process neural networks models. Firstly, the whole time-varying process is divided into several small time intervals; then, the process neural networks are constructed respectively in the small time intervals to disperse the...
Load shedding is a challengeable issue in data stream management systems (DSMSs). When data stream rates exceed system capacity, the overloaded DSMS fails to process all of its input data and keep up with the rate of data arrival. Especially, in a time-critical environment, queries should be completed not just timely but within certain deadlines. Existing strategies are poor at handling huge fluctuant...
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